01 -
Place the chocolate eggs in the freezer. (This will make them easier to cut cleanly and means they won't melt too much in the oven.) Grease and line a square 20cm cake tin. Preheat the oven to 180C/160C Fan/Gas 4.
02 -
Place the chocolate, butter and cocoa powder in a heatproof glass bowl and set it over a saucepan of gently simmering water, making sure the water does not touch the bowl. Stir until completely melted and then remove from the heat. In a separate bowl, whisk together the eggs, caster sugar, light brown sugar and vanilla until smooth. Pour into the chocolate mixture and mix well. Add in the flour and salt and mix until smooth. Stir in the shortbread. Pour the mixture into the prepared tin.
03 -
Take the chocolate eggs out of the freezer and slice them in half vertically. Nestle them into the brownie mixture, with the insides of the eggs facing up, and bake for 27–30 minutes until just set. Remove from the oven and leave to cool completely before slicing into squares.